President Obama nominated former Senator Chuck Hagel as the next U.S. secretary of defense. To those who haven't followed the Senate closely in the past decade, he's probably not a household name.

Hagel is a former GOP senator from Nebraska and Purple-Heart-decorated Vietnam veteran, but he wouldn't necessarily be a popular pick with Republicans in Congress.

At age 21, Hagel and his brother Tom became the next in the family to serve in the United States Army. They joined the masses of Americans fighting an unfamiliar enemy in Vietnam.

In his book, he describes finding himself "pinned down by Viet Cong rifle fire, badly burned, with my wounded brother in my arms."

"Mr. President, I'm grateful for this opportunity to serve our country again," Hagel said after Obama announced his nomination Monday.

In 1971, Hagel took his first job in politics as chief of staff to Congressman John Y. McCollister, a position he held for six years. After that, he moved to Washington for the first time, where he went on to work for a tire company's government affairs office, the 1982 World's Fair and in 1981, as Ronald Reagan's Deputy Administrator of the Veterans Administration.

He worked in the private sector for most of the 80s and 90s before his first election to the Senate in 1997.
Since the turn of the century, Hagel has followed a curvy path of political alliances that puts his endorsements all over the map. Hagel's record of picking politically unpopular positions could be a large part of why Obama is naming him for the job, as Slate's Fred Kaplan surmises the next Defense secretary will be faced with tough choices.

In 2000, he was one of few Republican senators to back Sen. John McCain over then-presidential-candidate George W. Bush.

After that election, Hagel fiercely criticized Bush for adding 30,000 surge troops to Iraq, in place of the bipartisan Iraq Study Group's proposal of a draw-down and regional diplomacy, which Hagel preferred. When Bush instead announced that more troops would go to Iraq, Hagel co-sponsored a nonbinding resolution to oppose it, along with then-Sen. Joe Biden, D-Del.

"The president says, 'I don't care.' He's not accountable anymore," Hagel told Esquire in June 2007. "He's not accountable anymore, which isn't totally true. You can impeach him, and before this is over, you might see calls for his impeachment. I don't know. It depends how this goes."

Hagel's fierce opposition to America's involvement in Iraq – he called it one of the five monumental blunders of history, on par with the Trojan War – will be of substantial importance as the Obama administration charts our course out of Afghanistan, deciding how to withdraw the last of the troops in 2014 and how much of a presence to leave behind.

Hagel's support for McCain, which was substantial in his competition against Bush, disappeared in the 2008 election. Hagel toured Iraq and Afghanistan with Obama during his first campaign for the presidency.

In October 2008, Hagel's wife, Lillibet, announced her support for the Obama team, after the Washington Post reported on her donations to his campaign. She donated again in 2012.

Before the 2008 election, Hagel wrote: "The next president of the United States will face one of the most difficult national security decisions of modern times: what to do about an Iran that may be at the threshold of acquiring nuclear weapons."

Hagel opposes unilateral sanctions against Iran, and while his multilateralist approach fits with President Obama's, Hagel's votes against extending sanctions on Iran could cost him favor with Israel advocates.

The Republican Jewish Coalition aired a list of grievances against Hagel in December, after his name first became seriously floated for the position, with Executive Director Matt Brooks saying the former senator's "statements and actions regarding Israel have raised serious concerns for many Americans who care about Israel."

Weekly Standard editor William Kristol, who also leads the Emergency Committee for Israel, lambasted Hagel in an editorial in his magazine, citing Hagel's "anti-Israel, pro-appeasement-of-Iran bona fides," and, "record of consistent hostility to Israel over the last decade."

Shortly after Obama made his announcement, Senate Majority Leader Eric Cantor released a statement saying he was "profoundly concerned and disappointed" with Hagel's nomination.

"Senator Hagel's incendiary views of Israel are only the tip of the iceberg. On Iraq, Afghanistan, Syria, Iran and defense spending, Hagel's reported views call into question his judgment about the most important matters facing our national security. Taken together, Hagel's views represent a call for a broad retreat from the preeminent role America has played, and must continue to play, in the world during a period of profound tumult and instability," Cantor, R-Va., wrote.

A Republican LGBT activist group has also criticized Hagel for his record on gay rights, for – among other things – opposing the repeal of Don't Ask, Don't Tell.

In a 2011 interview with the National Journal, Hagel said "a dangerous, toxic intolerance of other people's opinions" had tainted American politics.

Though he has largely shown support for President Obama, he called the president's health care law his "biggest mistake," saying it sapped him of "a good amount of his political capital and goodwill going in."

By picking Hagel, a Republican, Obama is seen as making a stab at bipartisanship – something most Americans agree Washington is sorely lacking these days.

Immediately after Obama announced his nomination, former Secretary of State Colin Powell sent out a statement endorsing his choice.

"Chuck displays his courage in many ways. You can always count on him to analyze a difficult situation and take a position that reflects his best judgment. I believe that more than ever we need that kind of independent and bold leader who thinks in and out of the box. He is the kind of leader needed by the Department of Defense to deal with the strategic and resource challenges it will be facing over the next several years."

Like Obama, Powell urged the Senate to confirm Hagel "as soon as possible."